This invention relates to an electronic computer sewing machine, and more particularly to a device for forming finish-up stitches thereof.
The finish-up stitches are formed after or during forming pattern stitches, and they are useful to prevent ravellings and as a sign of finishing the stitching.
The finish-up stitching has been hardly effective in a case of a needle dropping at the same position as the last pattern stitch, and since such a condition has damaged thread, needle dropping positions have been changed but not in a needle amplitude direction, i.e. transverse or oblique to the fabric feeding direction. Stitching data composed of only fine fabric feedings have been determined for applications to all stitching patterns.
However, if such determined finish-up stitching data is used, the patterns are not deformed with respect to stitched parts which are parallel to the fabric feeding direction (along vertical directions in the drawing of FIG. 1) in a straight stitching or a stitching pattern as shown in FIG. 1(A). But, with respect to the stitching patterns containing components in a needle amplitude direction as shown in FIG. 1(B), if the finish-up stitching data is changed in the fabric feeding direction only, the parts of the finish-up stitching are unsightly deformed.
As an improvement therefor, by storing a plurality of stitching data concerning the finish-up stitching in a program memory (ROM), a method has been proposed which selected appropriate finish-up stitching data in response to the patterns before forming the finish-up stitching or a stitching coordinate (Japanese Patent Disclosed Patent Document 194,782/84 "A method of finish-up stitchings in an electronic computer sewing machine"). This method has the following disadvantages:
(1) A plurality of stitching data are required, but the programming memory (ROM) is inferior in efficiency. PA0 (2) Since the stitching data is used, the length to be taken for the finish-up stitching is made fixed, and if changings of the stitching coordinate before forming the finish-up stitching as shown in FIG. 1(C) are smaller than the length of the finish-up stitching, the finish-up stitching part is unsightly deformed.